This invention relates in general to locks and more particularly to keepers or strikes for locks.
Wood doors and door frames are widely used in residential and apartment construction for interior as well as exterior entries. While wood is attractive in appearance and easy to work, it is not from the standpoint of security ideally suited for dwelling entries.
Quite often a thief attempting to break into a home or apartment secured with a wood door and frame will merely kick in the door so-to-speak. Actually the thief delivers a heavy blow to the door in the vicinity of its lock, and usually the door frame splits under the force, thus freeing the door so that it swings inwardly on its hinges and allows the thief to gain entry to the dwelling. In this connection, most locks project a bolt from the door into the door frame to secure the door, and the door frame is normally provided with a hole and an apertured strike or keeper which surrounds the hole. The hole and the screws which hold the keeper in place weaken the door frame to the extent that it splits along the grain passing through them when the heavy blow is transmitted to the frame through the lock.
Aside from the foregoing, a door when closed fits against a stop on the door frame, and in order for the door to be secured firmly against this stop, the keeper must be installed with a considerable degree of precision. For example, if the keeper is set too close to the stop, the bolt will not throw and the door cannot be secured. On the other hand, if the keeper is set too far away from the stop, then the door does not fit tightly against the stop, enabling one to insert a credit card or other thin object between the edge of the door and the keeper to force the latch bolt back and thereby gain entry. Furthermore doors or frames sometimes warp, and as a result the keeper must be reset, but this is difficult and often weakens the frame still further. Thus, the installation of a lock, and particularly its keeper, requires a considerable amount of carpentry skill.